1. Field of the Invention
The present invention relates to a method for etching a piezoelectric film and a method for manufacturing a piezoelectric element and, in particular, relates to a method for etching a piezoelectric film and a method for manufacturing a piezoelectric element, in which the etching is performed by wet etching.
2. Description of the Related Art
A piezoelectric element formed of a piezoelectric material which expands and contracts in response to an increase and decrease in electric field application intensity is used as an actuator, a sensor, a recording element, or the like which is mounted in an ink jet recording head. As a method for forming a pattern of a piezoelectric material, a wet etching process using an etchant is used.
For example, JP4665025B describes, as a method for processing an epitaxially grown PZT film, an etching method using at least one of hydrochloric acid and nitric acid and at least one fluorine compound of ammonium fluoride and hydrogen fluoride. JP3201251B describes a technique of patterning a dielectric through two steps of: etching a dielectric with an etchant which is composed of hydrofluoric acid and sulfuric acid or hydrochloric acid; and removing a residual portion with a post-treatment solution which is composed of acids. By etching a dielectric through the two steps, the selectivity with a photoresist can be improved.
In addition, JP2004-031521A describes a technique of performing patterning using an etchant containing one of hydrogen fluoride (HF), buffered hydrofluoric acid (BHF), diluted hydrofluoric acid (DHF), sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). JP1988-285011A (JP-S63-285011A) describes a method in which, in order to etch a metal film on a piezoelectric substrate material with high accuracy, the metal film is dry-etched in an initial stage and then a final residual portion is wet-etched. JP2012-244090A describes a technique of using a chromium film as a mask for the wet etching of a piezoelectric film.